This study aims to explore the impacts of differences in constructive species on soil fungal diversity in cold temperate Larix gmelinii forests, which is expected to provide useful reference for the construction of L. gmelinii forest communities and the maintenance of soil fungal diversity.

The vegetation survey was conducted in the monitoring plot of larch forests in the Greater Khingan Mountains, the important values of L. gmelinii were calculated and used as the experimental treatments. The soil was sequenced by Illumina MiSeq high-throughput sequencing technology to analyze the changes of soil fungal community composition and diversity under the difference of constructive species, and to explore the soil environmental factors affecting its changes.

The soil physical and chemical properties of L. gmelini forests were significantly difference (P < 0.05). The soil AP contents increased significantly with the increase of L. gmelini important value, while soil SOC, MBC, pH and C/N showed a significant downward trend. A total of 463 species of soil fungi belonging to 14 phyla, 47 classes, 96 orders, 176 families and 298 genera were obtained by sequencing. Basidiomycota and Ascomycota were the dominant fungal phyla. Except for Mucoromycota, the relative abundance of other phyla was significantly different (P < 0.05). The dominant genera of larch forests were different, and the relative abundance of each genus was significantly difference (P < 0.05). The results of Chao1, Shannon and Simpson indexes showed that there was no significant difference in the Alpha diversity of soil fungi in L. gmelini forest (P > 0.05). NMDS analysis showed that the Beta diversity of soil fungi was significantly difference (P=0.001). Soil pH, AN, MBC, C/N, SOC, TN, AP and WC were the influencing factors of significant differences in soil fungal community structure. The results of functional prediction showed that the main trophic modes of soil fungi were Symbiotroph, Saprotroph and Saprotroph-Symbiotroph, and Ectomycorrhizal fungi were the most important functional groups. As increase of the important value of L. gmelinii, the Ectomycorrhizal decreased significantly (P < 0.05).

The composition, diversity and potential function of soil fungal community in L. gmelinii forests with different important values of constructive species were significantly different, and the difference of soil physical and chemical properties was the main influencing factor.